The present disclosure relates to methods and compositions for screening surfactants for use in downhole operations.
During many wellbore operations, aqueous fluids are injected into a subterranean formation to stimulate the formation by forming or expanding fluid flow paths within the formation to enhance later hydrocarbon production. Exemplary flow paths may include pore spaces, microfractures, fractures, intestinal space of proppant packs, and the like. After stimulation operations, the aqueous fluid may then be removed from the formation by a flowback operation where the fluid pressure in the wellbore is manipulated to allow for the aqueous fluid to flow from the formation back to the wellbore and the hydrocarbons to displace the aqueous fluids in the flow paths. Because the aqueous fluid and formation hydrocarbons are often immiscible, residual aqueous fluid in the flow paths may act to block the flow of hydrocarbons therethrough and reduce the hydrocarbon production of the well.
In some instances, surfactants are included in aqueous fluids to decease the surface tension and interfacial tension between the aqueous fluid and hydrocarbons and/or the surfaces of the flow paths, which may allow for greater aqueous fluid flow though the flow paths, more effective flow back operations, and ultimately greater hydrocarbon production. The interfacial tension values and wetting properties for surfactants may be used as an indicator of the surfactant's suitability for use in fluids where flowback is desired. However, in recent years, the number of surfactants sold for use in hydrocarbon exploration has increased significantly. Further, many surfactants have similar surface tension or interfacial tension values and wetting properties. Therefore, there is a need for a highly sensitive method of evaluating surfactants and their ability to increase aqueous fluid flowback in downhole operations.